Satechi is the latest manufacturer to release a super-high capacity rechargeable battery pack compatible with Apple's Dock Connector-equipped devices. With somewhat better build quality than one might expect for the price, and a 5.5" x 2" x 0.75" hard plastic design that resembles an elongated black iPhone 4/4S, Portable Energy Station ($60) has a large 10,000mAh cell packed in. Two outputs allow you to charge a pair of devices at a time: oneā¦